Fonction cosmétique conservateurs

What is the purpose of preservatives?

Preservatives play a major role in cosmetic formulation, ensuring, as their name suggests, that products are preserved over time. But what exactly do they do to protect cosmetics? Find out here what preservatives are used for.

Summary
Published September 18, 2024, updated on September 20, 2024, by Pauline, Head of Scientific Communication — 11 min read

A closer look at the role of preservatives.

Acting to maintain the texture, smell, colour, and safety of a skincare product, a preservative is defined as follows by Regulation No. 1223/2009 of the European Parliament and Council relating to cosmetic products, establishing the rules that every cosmetic product made available on the European market must comply with: it is a "substance exclusively or primarily intended to inhibit the development of micro-organisms in the cosmetic product". If cosmetics are generally very sensitive to bacterial contamination, it is because of their high water content. Indeed, just like humans, micro-organisms cannot survive without water and tend to proliferate in aqueous environments.

Preservatives therefore play a crucial role in ensuring the safety of skincare products. Indeed, in addition to deteriorating the organoleptic characteristics of cosmetics, bacteria, fungi and other microorganisms can potentially increase the risk of allergic reactions and irritations, particularly when applied to damaged skin, near the eyes or on the skin of babies. These adverse reactions can be explained by the ability of certain microorganisms to produce toxins that may damage the skin barrier or interact with the immune system. Other microorganisms can also directly interact with the active ingredients of the products, making them irritating.

Preservatives are antimicrobial agents that ensure the safety of cosmetics.

The various types of preservatives.

For a molecule to be classified as a preservative, it is not enough for it to have antimicrobial properties: it must be included in the list of preservatives permitted in cosmetic products, available in Annex V of European Regulation No. 1223/2009. This list also specifies in which type of product each preservative can be incorporated and in what quantity. 59 preservatives are currently listed. Among them, it is important to know that only five are authorised for use in organic cosmetics : benzoic acid, benzyl alcohol, sorbic acid, dehydroacetic acid, and potassium sorbate. Preservatives can be divided into two categories: synthetic preservatives and natural preservatives.

  • Synthetic Preservatives : Synthetic preservatives allow for a good understanding of the toxicity and safety of ingredients and are generally effective at low concentrations. Moreover, they have a fairly broad spectrum of activity against bacteria and fungi. The most commonly found synthetic preservatives are organohalogen compounds, such as triclosan and chlorphenesin, aldehydes such as formaldehyde and bronopol, glycol ethers, like phenoxyethanol and ethoxydiglycol, and parabens, such as methylparaben and butylparaben.

  • Natural Preservatives : Natural preservatives, which comply with the ISO 16128 standard, often have a better reputation than synthetic preservatives. Moreover, they can generally adapt to a wide pH range. The most commonly used natural preservatives are benzoic acid and sorbic acid.

There also exist compounds that possess antimicrobial preservation properties, but this is not their primary function: they are sometimes referred to as unlisted preservatives. This is the case, for example, with radish ferment extract (INCI: Leuconostoc/Radish Root Ferment Filtrate). Furthermore, certain molecules that help to preserve cosmetics from degradation due to exposure to oxygen (antioxidant function) or UV light (photoprotective function) can also be added to cosmetics. Although they are not strictly considered as preservatives by European Regulation No. 1223/2009, they are commonly used to extend the shelf life of products. Among these "pseudo" preservatives, we notably find vitamin E.

What preservatives can be found in Typology skincare products?

In line with our formulation charter, at Typology, we exclude preservatives suspected of being harmful to health. We frequently use o-cymen-5-ol, a synthetic preservative, and dehydroacetic acid, a natural preservative, both of which have a good safety profile. Additionally, to improve the preservation of our treatments, we often add radish ferment extract and the bacteria Lactobacillus ferment, unlisted preservatives.

Is preservative-free skincare possible?

It is possible for certain cosmetics to be formulated without preservatives without endangering consumers: these are products that possess only an oily or anhydrous phase. As stated above, in the absence of water, microorganisms such as bacteria, yeasts, and moulds cannot grow. Therefore, it is not necessary to add preservative agents. These products are most often based on vegetable oils, butters or waxes and thus have a natural microbiological stability. Other cosmetics need to be composed of at least one preservative.

Note : Consumers play a crucial role in the proper preservation of their cosmetic products. Adhering to the use-by dates, periods after opening, storing the products in a cool, dry place away from light, and regularly checking their organoleptic properties (colour, texture, smell...) are key behaviours to adopt.

What is the complete list of preservatives?

The 59 preservatives listed by European Regulation No. 1223/2009 and appearing in Annex V are compiled in the table below.

Chemical NameMaximum Concentration
Benzoic Acid and its Sodium Salt2.5% (acidic) for rinse-off products, 1.7% (acidic) for rinse-off oral care products, and 0.5% (acidic) for leave-on products
Propionic Acid and its Salts2% (acid)
Salicylic Acid and its Salts0.5% (acid)
Sorbic Acid and its Salts0.6% (acid)
Formaldehyde and Paraformaldehyde0.1% (free formaldehyde) for oral care products and 0.2% (free formaldehyde) for other products
Biphenyl-2-ol and its salts0.2% in phenol
Zinc Pyrithione1% for haircare products, 0.5% for others
Inorganic Sulphites and Bisulphites0.2% in free SO2
1,1,1-Trichloro-2-methylpropan-2-ol (Chlorobutanol)0.5 %
p-Hydroxybenzoic acid, its salts and esters0.4% in acid for an ester and 0.8% in acid for ester mixtures
Dehydroacetic Acid and its salts0.6% (in acid)
Formic acid and its sodium salt0.5% (in acid)
1,6-Di (4-amidino-2-bromophenoxy)-n-hexane (Dibromohexamidine) and its salts (including isethionate)0.1%
Sodium Ethylmercurithiosalicylate (Thiomersal)0.007% (in Hg)
Phenylmercury and its salts (including borate)0.007% (in Hg)
Undecylenic Acid and its Salts0.2% (in acid)
1,3-bis(2-ethylhexyl)hexahydro-5-methyl-5-pyrimidinamine0.1%
1,3 Bromo-5-nitro-5 dioxane0.1%
Bromo-2 nitro-2 propanediol 1,3 (Bronopol)0.1%
2,4-Dichlorobenzyl Alcohol0.15%
1-(4-Chlorophenyl)-3-(3,4-dichlorophenyl)urea0.2%
Chlorocresol0.2%
5-Chloro-2-(2,4-dichlorophenoxy) phenol0.3%
Chloroxylenol0.5 %
N,N''-Methylenebis[N'-[3-(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl]urea]0.6%
α, ω-bis [[[(Aminoiminomethyl)amino]iminomethyl] amino]poly(methylene), dichloride0.3%
Phenoxy-2-ethanol1.0 %
Methenamine0.15%
1-(3-Chloroallyl)-3,5,7-triaza-1-azoniaadamantane Chloride0.2%
1-Imidazolyl-1-(4-chlorophenoxy) 3,3-dimethylbutan-2-one0.5 %
Dimethylol, Dimethylhydantoin0.6%
Benzyl Alcohol1.0 %
1-Hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)-2-pyridone and its monoethanolamine salt1.0% for rinse-off products, 0.5% for others
2,2'-Methylenebis(6-bromo-4-chlorophenol)0.1%
Isopropyl-Metacresol0.1%
Chloro-5-methyl-2-isothiazolin-4-one-3 + methyl2-isothiazolin-4-one-3 + magnesium chloride and magnesium nitrate0.0015%
Benzyl-2-chloro-4-phenol0.2%
Chloracetamide0.3%
N,N''-bis(4-Chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine: acetate, gluconate and hydrochloride0.3% (in chlorhexidine)
Phenoxypropanol 1.0 %
Alkyl (C12-22) trimethyl ammonium, bromide and chloride0.1%
4,4-Dimethyl-1,3-oxazolidine0.1%
N-(Hydroxymethyl)-N-(dihydroxymethyl-1,3-dioxo2,5-imidazolidinyl-4)-N-(hydroxymethyl) urea0.5 %
4,4'-(1,6-Hexanediylbis(oxy)) bis-benzenecarboximidamide and its salts (including isethionate and p-hydroxybenzoate)0.1%
Glutaraldehyde (1,5-pentanedial)0.1%
5-Ethyl-3,7-dioxa-1-azabicyclo[3.3.0] octane0.3%
3-(p-Chlorophenoxy)-propane-1,2-diol 0.3%
Sodium Hydroxymethylaminoacetate0.5 %
Silver chloride deposited on titanium dioxide0.004% (in AgCl)
Chloride of N,N-dimethyl-N-[2-[2-[4-(1,1,3,3-tetramethylbutyl)phenoxy]ethoxy]ethyl]benzenemethanaminium0.1% for rinse-off products
Benzalkonium Chloride, Bromide and Saccharinate0.1% (in benzalkonium chloride)
(Phenylmethoxy) Methanol0.15% for rinse-off products
3-Iodo-2-propynylbutyl Carbamate0.02% for rinse-off products, 0.01% for leave-on products, and 0.0075% for deodorants
2-Methyl-2H-isothiazol-3-one0.01%
Liste des 59 conservateurs admis par la réglementation européenne.
Source : Règlement (CE) n°1223/2009 du Parlement Européen et du Conseil.

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